Module 2 – Number Sense: Part 2

Getting Started
  1. Review the module introduction and outcomes to help you gain an understanding of the main topics and expectations.
  2. Work through each lesson in this module and complete the Check Your Knowledge activity.  You can take notes on each lesson by clicking on the “take notes” tab on the bottom right of your screen. You can take notes for each lesson and they will appear on your dashboard. Make sure you save your notes before continuing to another lesson or quiz.
  3. Complete the Module Quiz and Module Evidence Activity on this page once all lessons are finished in full.

Note: If you would like to learn more about this module’s topics, click the Module Toolbox or Module Glossary for additional and supplementary resources.

In Number Sense, Part 2, students will continue working with real world applications of ratio, unit rates, and percentage applications. They will learn to convert decimals, fractions, ratios, and percentages from one form to another as needed. This foundation will lead to advanced problem solving such as sales tax, discounts, and simple interest. Students will learn more mental math by solving percentages without the use of calculators or pencils.


After completing this Module, you should be able to:

  • Demonstrate computations and order decimals
  • Solve multi-step arithmetic and real-world problems involving exact percents.
  • Solve real-life problems requiring interpretation and comparison of various representations of ratios, and simplify numerical expressions with rational exponents.
  • Solve tax, discount, and simple interest problems using the techniques provided.
  • Calculate common percents mentally.


Lesson 1 – Decimals

AJAX progress indicator
  • decimal point
    the dot placed between the whole number and fractional part of a decimal
  • equivalent decimals
    two decimals that have the same value, but are not written the same

Lesson 2 – Ratios and Proportions

AJAX progress indicator
  • rate
    compares two different types of measurements, such as miles to gallons
  • unit price
    a unit rate for one item
  • unit rate
    a rate with a denominator of one

Lesson 3 – Rational Numbers

AJAX progress indicator
  • percent
    a ratio whose denominator is 100
  • rational numbers
    numbers that can be written as a ratio of two integers

Lesson 4 – Percent Applications

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  • discount
    a percent off the original price
  • interest
    the money the bank pays you for investing your money
  • percent
    a ratio whose denominator is 100
  • principal
    money you put in the bank
  • rate of interest
    how much interest you gain based on a percent of the principal; expressed as a percent per year
  • sales tax
    a percent of the purchase price

Lesson 5 – Application: Mental Percents

AJAX progress indicator
  • 100%
    the whole number
  • 200%
    double the number
  • 25%
    "quarter of the number" or "half of a half"
  • 5%
    half of 10%
  • 50%
    half the number
  • multiples of 10%
    10% of a number times the multiplier
  • multiplier
    the number you are multiplying by